Un-schedules all previously-scheduled cron jobs using a particular hook name and arguments.
<?php wp_clear_scheduled_hook('my_schedule_hook', original_arg1, arg2, ... ); ?>
Note that you need to know the exact function arguments this cron hook was supposed to have, in order to unschedule it. All ocurrences of this hook in the schedule, with these arguments, will be removed from the schedule. Also note that the arguments are passed-in singly, not in an array as in the other cron-related functions.